The Government agreed to wipe out the UK's ruddy duck population after it was found the north American duck was challenging the survival of the globally-threatened white-headed duck through interbreeding.

New scientific information from the U.S. Fish and Wildlife Service suggests the spotted owl is not entirely dependent on old-growth forest for habitat and faces a significant threat from interbreeding with the barred owl.

Wild Atlantic salmon stocks will be wiped out within decades because of interbreeding with escaped farmed stocks, leading scientists have warned.